Control system for electric motors



Dec. l5, 1936. J, F. PRESE 2,064,303

CONTROL SYSTEM FOR ELECTRIC MOTORS.

Filed Jan. 4, 1936 Patented 15, 1936 UNITED STATES PATENT oFFic-E CONTROL SYSTEM FOR ELECTRIC MOTORS Joseph F. Frese, Baltimore., Md., assignor to Monitor Controller Company, Baltimore, Md., a corporation of Maryland AApplication! January 4, 1936, Serial No. 57.610

Clnlmf. (Cl. 173-179) circuit. For controlling the speed of the motor,

I provide a series of contactorsleach adapted to control a section of the resistance in the arma-V ture circuit of the motor and each having an energizing coil and a retarding coil, the latter being in the armature circuit, and certain of the contactors having interlocking switches for connecting the energizing coils of the other contactors to the supply circuit. A pre-set speed switch is provided for connecting the individual energizing coils of the speed controlling contactors to the supply circuit and for connecting the energizing coil of each contactor to the supply circuit through the interlocking switch of another contactor, whereby when more than one contactar is operated they will operate in sequence to cut out sections of the resistance and whereby any part or all of the resistance may be cut out or left in circuit to control the speed of the motor.

In the drawing, wherein the invention is shown diagrammatically, M indicates a direct current electric motor comprising the amature I, series field winding 2 and shunt neld winding l, and L. L' indicate the supply wires leading from a current source. The shunt neld circuit extends from supply wire L through conductor 4 to winding s, thence through conductor s to an adjustable tleld regulating resistance t and thence by con' ductor 1 to supply wire L. A contactor A is provided for connecting the armature to the supply wires i'or operation of the motor and its load in the normal or forward direction, and contactor B is provided for reversing the connections to cause the motor to turn baclrwardly.l For closing the armature circuit, the contacter A has two normally open switches a and o', and the Acontactar B has two normally open switches b and b' fory the same purpose. Contact l oi' switch@ is con-'- nected by conductor t to contact Il of switch b, and contact H of switch a' is connected by conductor I2 to contact I3 of switch b.-

When the contacter A is closed, to operate the motor in the 'forward direction, the armature oir- .Il and I2 to switch a', thence by cuit of the motor is completed as follows: from supply wire L through conductor I4 to the series field winding. and by conductors l5 Vand Il 'to switch a, thence by conductor I1 to the armature, thence by conductors conductor I9 to resistance sections R3, R.2 and R1 and by conductor 20 to and through lock-out coils 2|, 22 and 23 of speed controlling contactors E,

D and C, respectively, and thencelby conductor 24 to supply wire L',

' When the reverse contactor B is closed, the armature circuit is completed as follows: from supply wire L through conductor I4, series field winding 2 and conductor l5 to contact 2l of switch b'. thence to contact Il and by conductor i8 to the amature of the motor, thence by conductor l1 to contact 8 of switch a and by conductor 9 to contact I 0 of switch b and thence through the latter switch to conductor 28, thence by conductor I9 to resistance sections R3, Itz and R1 and by conductor 2U to lock-out coils 2|, 22 and 22, and thence by conductor 24 to supply wire L.

A dynamic brake circuit is connected to the armature terminals through conductors l1 and I8, this circuit comprising the conductor I1, brake resistance 21 and conductor lll. A contacter F, controlled by relay G, opens this circuit when the actuating coil of either of the contactors A or B is energized and closes the circuit when the actuating coil is de-ener'gized. The circuit for the coil of contactor F is from conductor I 5, which is connected to the. supply wire L through the series field winding, by conductor 2l to normally closed relay switch' G, thence by conductor 29 to coil 3l! of contacter F and thence by conductor Il to supply wire L. Normally the relay G is closed land hence normally the coil of contactor F is energized and this contacter maintains the dynamic brake circuit closed whilethe motor is stopped.

To energize the coll 22 of contactar A, a push button switch marked Fbrward" is depressed and a circuit through the coil and also through the coil 3l of relay Gis completed as follows: from supply wire L through conductor 24 to contacts 25, It, 21 and 2l, thence through conductor Il to coil J2, thence by conductors 4l andvll to coil of relay G and thence by conductor 42 to supply wire L. Upon` closure of this circuit, the contacter A will close the armature circuit to ton,'the circuit through coils 32 and I3 will be broken, contacter A will open the armature circuit, relay G will close the circuit through the coil 30 of contacter F and the latter contacter will close the dynamic brake circuit to brake the motor.

To energize the coil of contacter B, the push button switch marked Reverse" will be depressed and a circuit will be established as follows: from supply wire L through conductor 34 to the push button switch, thence by conductor 43 to coil 44 of contacter B, thence by conductors 40 and 4| to coil 33 of relay G and thence by conductor 42 to supply wire L'. Upon closure of this circuit, contacter B will close the armature circuit for backward rotation of the motor, relay G will open the circuit of the magnet of contacter F and the latter contacter will open the dynamic brake circuit. When the Reverse push botten is released, the coils of contacter B and relay G will be de-energized, the contacter will open the armature circuit and the relay will close the circuit through the magnet coil of contacter F and the latter contacter will close the dynamic brake circuit to brake the motor.

The Reverse push button switch is used only for operating the motor to jog the press backwardly and the contacter B remains closed only while the switch is held in closed position. In operating' the press backwardly, it is desirable that the motor shall operate only at slow speed, and, therefore, all of the regulating resistance remains in the armature circuit, the contactors C, D, and

E for controlling this resistance being inoperative. Also, when the Forward push button switch alone is depressed, the contacter A will close the armature circuit through all of the resistance, the contactors C, D and E being inoperative, and the motor will operate at slow speed to jog the press forwardly only so long as the push button is depressed.

When it is desired to operate the press continuously in the forward direction, a switch marked Run is closed to make up a holding circuit ior the coil 32 of contacter A, which holding circuit is completed by the contacter when it closes. This holding circuit extends from supply wire L through conductor 34 to the Run switch thence by conductor 45 to stationary contact 46 of a normally open switch a2 operated by the contacter A, thence to contact 41 which is connected to conductor 39 leaning to contacter coil 32. From the coil, the circuit continues through conductors 4U, 4|, relay coil 33 and conductor 42 to the supply wire L'. The contact 48 of Run switch is connected to contact 36 of the Forward switch by conductor 45. With the Run switch closed to make up the holding circuit te the switch a2, the momentary depression of the Forward switch will complete the circuit to the coil 32 through conductor 39, the contacter A will close the holding circuit atthe switch a, and the motor will continue to operate after the release of the Forward switch and until the Run switch is opened.

A switch H is provided for making up a circuit to the actuating coils of the speed controlling contactors C, D and E. While this switch is open, these contactors are inoperative to cut resistance. cut of the armature circuit. When this switch is closed, a circuit is made up to said actuating coils as follows: from supply wire L through conductor 34 to contact 49 of switch H, thence by conductor 50 to stationary contact 5| of a normally open switch a3 on contractor A, and from said switch. the circuit continues through conductor 52 to the actuating coils c, d and e of contactors C, D and E, in parallel. From coil c, a conductor 53 leads to a plurality of contacts c on a pre-set speed controlling switch mechanism J. Coil d is connected by conductor 54 to a plurality of contacts d on the switch mechanism J and coil e is connected by conductor 55 to a plurality of contacts e on said mechanism. These contacts may be grouped in various combinations by a relatively movable bridging device 7' adapted to connect some of them to the side L of the supply circuit through a long metal strip or bus bar 56 and conductor` 51, and others through interlocking connections controlled by contactors D and E.

The contacter D controls a normally open interlock switch -58 and when this contacter closes to cut out the resistance section R1, it also closes the switch 58 and thereby connects contacts da on the pre-setting switch with the side L' of the supply circuit as fellows: from L' through conductor 24 and lock-out coils 29, 22 and 2| to conductor 20, thence through conductor 59 to switch 58, thence by conductor 60 to the contacts d2. The contacter E controls a normally open interlock switch 6| and when this contacter closes to cuty out resistance section RX, it closes switch 6| and thereby connects a series of contacts e on the pre-setting switch to the side L of the supply circuit through conductor 24 and the lock-out magnet coils 23, 22 and 2|, thence through switch 6| and conductor 62 to the contacts e.

To operate the motor forwardly continuously under the control of the speed contactors C, D and E and the pre-set speed regulating switch mechanism, the switch H is closed to make up the circuit to the normally open switch a3 on contacter A and the coils of the speed contactors, and the run switch is closed to make up the holding circuit of coil 32 of contacter A to the normally open switch a2 on said contacter, and the forward push button is then momentarily closed to energize the coil 32. 'Ihe contacter A then closes the motor circuit and simultaneously closes the holding circuit at the switch ai| and the circuit to the coils of the speed contactors at the switch a3. 'I'he motor will then operate at a speed determined by the setting of the member y' of the pre-set speed regulating mechanism J.

The bridging device y has three alined contact members or bridge pieces 63, 64 and 65. If this device is in the rst or low speed position, as shown in the drawing, when the armature circuit is closed, no one of the contacts connected to the energizing coils of the speed controlling con.

tactors will be engaged and the motor will operate at its slowest speed, with all of the resistance in the armature circuit.

'I'he resistance oi' the sections R3, Rz and R1 increases geometrically, the resistance of section R2 being twice that of section R1' and the resistance of section Rl being twice that oi section R.

If the bridging device is set in the second speed position, the contact member 63 will connect a contact c' to the bus bar and thence to the supply wire L and complete the circuit through the energizing coil c of contacter C., This coil is opposed by the lock-out coil 23 in the armature circuit, and when the current in said circuit falls to a preedetermined value, the contacter will close and cut out the resistancey section R3, leaving sections R2 and R1 in the circuit. 1

If the bridging device is in the thirdspeed position when the armature circuit is closed, the

contact member 4B3 will connect a contact. d to the bus bar and thence to .supply wire L' and complete the circuit of the energizing ceil d of contacter D. This contacter will close when the current in the lock out coil 22 falls to a pre-determined value and section R2 ofthe resistance will be cut out of the armature circuit, leaving sections R3 and R1 in the circuit.

It the bridging device is set in the fourth4 speed position, the contact member B3 will connect a terminal d of the energizing coil of contacter D to the side L of the supply circuit through the bus bar and conductor 51, and the contact member 6I will connect a terminal c of the energizing coil oi'centactor C to a contact d1 which is connected through conductor 60 to switch 58 ot contacter D. Contacter D will close when the current in lock-out coil 22 falls to a pre-determined value, cutting out the resistance section R2, and switch 5I will close completing the circuit of the coil c of contacter C through conductorsy 59 and 60, bridge piece 6l and conductor 53. Contactor C will then close when the current in the lock-out coil 23 permits. The motor will then operate with only the resistance section R1 in the armature circuit.

If the bridging device is set in the fth speed position, its contact member 63 will connect a terminal e' of the energizing' coil of contacter E to supply wire L' through the bus bar, and contacter E will close when the current in its lock-out coil 2| permits. In this position of the bridging device, the resistance section R1 will be cut out ef the armature circuit and the sections R2 and R.3 will remain in the circuit.

In the sixth speed position of the bridging device, contact member B3 will connect a terminal e' of the coilv of contacter E to supply wire L' and bridge piece 8l will connect a terminal c' of the energizing coil oi' contacter C to a contact c2 which is connected by conductor 62 to a contact on the switch 6i which is controlled by contacter E. Contacter E will first close, when the current in its lock-out coil 2| permits, cutting out resistance section R1, and the switch 6| will complete the circuit to energizing coil of contacter C through conductors B2 and 5,3. Contacter C will then close, cutting out resistance section R3, and the motor will operate with the resistance section R2 in the armature circuit.

In the seventh speed position of the bridging device, its contact member 83 will connect a terminal e of the energizing coil of contacter E te the' side L' of the supply circuit through the bus bar, and the contact member 64 will connect a terminal d' of the energizing coil of contacter D to a'terminal e2 which is connected to the switch 8| controlled by contacter E. Contacter E will nrst close, cutting out resistance section R1. and the switchl will complete the circuit of the coil d of the contacter D, and the latter will then close, cutting out resistance section R1, and the motor will then operate with the resistance section Rain its armature circuit.

In the eighth or fast speed position of the bridging device, the bridge piece 83l connects a terminal e' of the energizing coil of contacter E to supply wire L through the bus bar; bridge piece M connects a terminal d of the energizing coil of contacter D te a contact es connected by conductor 62 to switch 6I of contacter E, and bridge piece 65 connects a terminal c of the energizing coil of contacter C to a contact dz connected by conductor SII te the switch 5I controlled by contactorD. Contacter E will first close, retarded by its lock-out coil, cutting out the section R1 of the resistance and closing switch 6i. This switch will close the circuit to the energizing coil d of contacter D through conductor 62, bridge piece 64 and conductor 54. Contacter D will then close, retarded by its lockout coil 22, cutting out resistance .R2 and clesing switch 58. The closure of switch 58 completes the circuit to energizing coil c of contacter C through conductor 60, bridge piece 65 and conductor 53. Contacter C. then closes, cutting out resistance section R3. The motor will then operate at full speed with all oi the resistance out of the armature circuit.

Thus, in all cases Where more than one of the contacters operate, they will operate in sequence.

What I claim is:

1. In a control system for electric meters, a supply circuit, a motor, two normally open contactors, one for closing the armature circuit for operation of the motor in one direction. and the other for closing said circuit for operation of the motor inthe reverse direction, circuits and switches fer controlling said contactors independently, a dynamic brake circuit, a relay having a coil connected to the supply circuit and normally closing the dynamic brake circuit when the motor is stepped, said relay adapted to open the brake circuit when its coil isl rie-energized, and a second relay normally closing the circuit of said first mentioned relay, said second relay having its coil connected in the control circuits of said contactors and adapted to open the circuit of the coil of the rst mentioned relay. to de-energize the same, when either of said control circuits is closed.

2. In a control system for electric meters, a supply circuit, a motor, a resistance in the armature circuit of the motor, a plurality of normally open contactors for cutting out said resistance, each of said contactors having an energizing coil, a normally open main contacter for connecting the motor to the supply circuit, a circuit for connecting the energizing coils o! said ilrst mentioned contactors to one side of the supply circuit including two switches in series, one ef said switches being controlled by the .main contacter and the other switch being manually operable, and a pre-set speed controlling device for connecting said energizing coils in various groupings to the other side of the supply circuit.

3.In a control system for electric motors, a supply circuit, a motor, a resistance in the armature circuit of the motor, a plurality of normally open contactors for cutting out said resistance, each of said contactors having an energizing coil for closing the contacter and a coil in series with the armature for retarding .the contacter, a normally open main contacter for connecting the motor to the supply circuit, a circuit for connecting the energizing coils of said first mentioned contactors to ene side of the supply circuit including two switches in series, one of said.

tors for cutting eut resistafricafleachfof said l contacters having anll'energizing coil.,

tain oi said contactors having normally open interlock switches for connecting the energizing coils of other of said contactors tc one side ot said supply circuit, a pre-set speed switch having means for connecting the energizing coils of said contactors individually to the aforesaid side oi' the supply circuit and also having means for connecting the energizing coil of each contactor to the interlock switch of another of said contactors, a main contactor for closing the armature circuit of the motor and a switch controlled by the latter contacter for connecting said energizing coils to the other side of the supply circuit when the main contactor closes.

5. In a control system for electric motors, a supply circuit, a motor, a resistance in the armature circuit of the motor, a plurality of contactors for cutting out said resistance, each of said contactors having an energizing coil and a retarding coil; the latter in the amature circuit, and certain of said contactors having normally open interlock switches for connecting the energizing coils o! other ci.' said contactors to one side o! said supply circuit, a pre-set speed switch having means for connecting the energizing coils of said contactors individually to the aforesaid side of the supply circuit and also having means for connecting the energizing coil of each contactar to the interlock switch of another of said contactcrs, a main contacter for closing the armature circuit of the motor and a switch controlled by the latter contactor for connecting said energizing coils to the other side of the supply circuit when the main contactar closes.

8. In a control system for electric motors, a supply circuit, a motor, a resistance in the armature circuit or the motor, a plurality ci contactors for cutting out said resistance, each of said contactors having an energizing coil and retarding means and certain of said contactors having normally open interlock switches for connecting the energizing coils ci other of said contactors to one side ci the supply circuit, a preset speed switch having contacts connected to the several energizing coils and contacts connected to the several interlock switches and a bridsin device adjustable relatively to said contacts, said device adapted, in successive positions, to connect the energizing coils individually to the aforesaid side of the supply circuit and in certain oi' said positions to connect one or more of said coils to the interlock switch or switches oi' other contactors, a main contactar for closing the armature circuit of the motor, and a switch controlled by the latter contactar for connecting said energizing coils to the other side ci' the supply circuit. when the main contactor closes.

JOSEPH F. FRESE 

